The invention relates to a fitting for joining tubing in a vehicle air conditioning system and more particularly to a line fitting wherein the air conditioning system refrigerant is CO2 and the fitting militates against permeation/leakage of CO2 in the high pressures and high temperatures experienced during operation of the CO2 air conditioning system.
In assembly line manufacturing of vehicles, it is desirable that line fittings in an air conditioning system can be secured using a power nut driver rather than using a torque wrench. For this reason, peanut (i.e., block) fittings are often employed.
Conventional air conditioning systems have employed various refrigerants (e.g., Freon and R134a) having modest pressure and temperature ranges. Newer air conditioning and heat pump systems are being developed which use CO2 as the refrigerant. The CO2 systems operate at much higher pressures and temperatures. Fittings used for conventional systems typically employ rubber seals (e.g., O-rings) and cannot be used in CO2 systems because of high permeation and decompression damage to the seals.
It would be desirable to produce a fitting for use in an air conditioning system which militates against permeation of CO2 and decompression damage to seals in high pressure and high temperature systems.
Consistent and consonant with the present invention, a fitting for use in an air conditioning system which militates against permeation of CO2 and decompression damage to seals in high pressure and high temperature systems has surprisingly been discovered. The fitting of the present invention employs blocks secured together using a stud, a nut, and gaskets or seals having a low permeation to CO2, an ability to withstand high operating pressures and temperatures, and a resistance to decompression damage.
The block fitting for a CO2 air conditioning system comprises:
a male block including a first aperture having a first end and a second end, the first end of the first aperture of the male block is adapted to receive a tube end therein, the male block including a female annular bore surrounding the first aperture to form a channel having a generally u-shaped cross-section;
a female block including a first aperture having a first end and a second end, the first end of the first aperture of the female block is adapted to receive a tube end therein, the female block including an annular collar surrounding the first aperture of the female block and adapted to be inserted into the channel formed by the female annular bore of the male block, at least one of an inner surface of the annular collar and an inner surface of the channel having an annular groove formed therein, the first aperture of the male block and the first aperture of the female block being substantially concentrically aligned;
a primary seal disposed adjacent and surrounding the second end of the first aperture of the male block and adjacent and surrounding the second end of the first aperture of the female block;
a secondary seal disposed in the annular groove of the annular collar of the female block, the secondary seal comprising a material with low permeation to CO2; and
a fastener adapted to engage the male block and the female block to sealingly engage the female annular bore of the male block and the annular collar of the female block.